A conventional behavior controller for a vehicle is a behavior controller including control means for estimating a state of the vehicle when the vehicle is making a turn and controlling a yaw rate behavior of the vehicle based on the result of the estimation. The behavior controller has a continuously variable transmission for continuously varying rotation power of an engine. The control means controls a behavior of the vehicle by the continuously variable transmission.
The behavior control includes behavior controls by the engine, a brake, and the continuously variable transmission. The priority of the intervention of the behavior control is set in order of the behavior control by the continuously variable transmission, the behavior control by the engine, and the behavior control by the brake (for example, see Patent Document 1).
Moreover, a conventional motion controller for a vehicle includes steering force index detecting means, self-aligning torque estimating means, vehicle state quantity detecting means, front-wheel index estimating means, gripping performance estimating means, and control means.
The steering force index detecting means detects at least one of steering force indices including a steering torque and steering force applied to a steering system of the vehicle. The self-aligning torque estimating means estimates an actual self-aligning torque (actual road surface reaction torque) generated on a front wheel of the vehicle based on a detection signal of the steering force index detecting means. The vehicle state quantity detecting means detects a state quantity of the vehicle. The front-wheel index estimating means detects at least one of front-wheel indices including a side force and a front-wheel slip angle on the front wheel of the vehicle based on a detection signal of the vehicle state quantity detecting means. The gripping performance estimating means estimates gripping performance with respect to at least the front wheel of the vehicle based on a change in the estimated actual self-aligning torque with respect to the estimated front wheel index. The control means controls at least one of a braking force for the vehicle, an engine output, and a gear shift position according to the detection signal of the vehicle state quantity detecting means (for example, see Patent Document 2).
In the conventional device of Patent Document 1 described above, the control means estimates the state of the vehicle when the vehicle is making a turn based on a deviation between a target yaw rate and an actual yaw rate, and executes the behavior control when an unstable state of the vehicle such as understeer and oversteer is detected.
Here, by executing the behavior control by the continuously variable transmission in priority to the behavior control by the brake, an excessive reduction in torque by the brake is prevented not to bring discomfort to a driver. Moreover, by executing the behavior control by the continuously variable transmission in priority to the behavior control by the engine, the rotations of the engine are prevented from being excessively reduced.
In the conventional device of Patent Document 1 described above, however, the unstable state of the vehicle is detected based on the deviation between the target yaw rate and the actual yaw rate. Therefore, the behavior control is executed after the vehicle itself falls into the unstable state.
Accordingly, there is a problem that a delay in intervention of the behavior control brings discomfort to the driver.
In order to solve the problem, in the conventional device described in Patent Document 2 described above, the gripping performance of the front wheel is estimated based on a change in the actual self-aligning torque with respect to the side force on the front wheel of the vehicle or the front wheel slip angle in order to detect the unstable state of the vehicle in an early stage. The estimated gripping performance is used to detect a traveling state of the vehicle.
Here, the actual self-aligning torque is obtained by subtracting a friction component of a steering system from an actual reaction torque corresponding to the sum of a torque acting on a steering shaft by an steering operation of the driver and a torque output from an electric power steering device.
[Patent Document 1] JP 2001-191820 A
[Patent Document 2] JP 2003-312465 A